Nias Regency is a regency in North Sumatra province, Indonesia; it lies on the east side of Nias Island. The regency formerly covered the entire island, and had an area of 3,495.39 square kilometres following the creation of the new regency of Nias Selatan but prior to the creation of the new regencies of Nias Utara and Nias Barat and the independent municipality of Gunungsitoli from parts of Nias Regency. According to the 2010 census the reduced Regency had a population of 132,329. Its seat is Gunungsitoli, although the city is no longer administratively part of the Nias Regency.